/*
 * Created on 19 Jun 2006
 * Created by Paul Gardner
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */

package org.gudy.azureus2.pluginsimpl.local.messaging;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

import org.gudy.azureus2.core3.util.Debug;
import org.gudy.azureus2.core3.util.DirectByteBuffer;

import com.aelitis.azureus.core.networkmanager.Transport;
import com.aelitis.azureus.core.peermanager.messaging.Message;
import com.aelitis.azureus.core.peermanager.messaging.MessageStreamDecoder;

public class GenericMessageDecoder implements MessageStreamDecoder {
    public static final int MAX_MESSAGE_LENGTH = 256 * 1024;

    private final ByteBuffer length_buffer = ByteBuffer.allocate(4);

    private final ByteBuffer[] buffers = { length_buffer, null };

    private final String msg_type;
    private final String msg_desc;

    private List messages = new ArrayList();

    private int protocol_bytes_last_read = 0;
    private int data_bytes_last_read = 0;

    private volatile boolean destroyed;

    protected GenericMessageDecoder(String _msg_type, String _msg_desc) {
        msg_type = _msg_type;
        msg_desc = _msg_desc;
    }

    public int performStreamDecode(Transport transport, int max_bytes)

    throws IOException {
        protocol_bytes_last_read = 0;
        data_bytes_last_read = 0;

        long total_read = 0;

        while (total_read < max_bytes) {

            long bytes_read;

            int read_lim = (int) (max_bytes - total_read);

            ByteBuffer payload_buffer = buffers[1];

            if (payload_buffer == null) {

                int rem = length_buffer.remaining();
                int lim = length_buffer.limit();

                if (rem > read_lim) {

                    length_buffer.limit(length_buffer.position() + read_lim);
                }

                bytes_read = transport.read(buffers, 0, 1);

                length_buffer.limit(lim);

                protocol_bytes_last_read += bytes_read;

                if (length_buffer.hasRemaining()) {

                    total_read += bytes_read;

                    break;

                } else {

                    length_buffer.flip();

                    int size = length_buffer.getInt();

                    if (size > MAX_MESSAGE_LENGTH) {

                        Debug.out("Message too large for generic payload");

                        throw (new IOException("message too large"));
                    }

                    buffers[1] = ByteBuffer.allocate(size);

                    length_buffer.flip();
                }
            } else {

                int rem = payload_buffer.remaining();
                int lim = payload_buffer.limit();

                if (rem > read_lim) {

                    payload_buffer.limit(payload_buffer.position() + read_lim);
                }

                bytes_read = transport.read(buffers, 1, 1);

                payload_buffer.limit(lim);

                data_bytes_last_read += bytes_read;

                if (payload_buffer.hasRemaining()) {

                    total_read += bytes_read;

                    break;
                }

                payload_buffer.flip();

                messages.add(new GenericMessage(msg_type, msg_desc, new DirectByteBuffer(payload_buffer), false));

                buffers[1] = null;
            }

            total_read += bytes_read;
        }

        if (destroyed) {

            throw (new IOException("decoder has been destroyed"));
        }

        return ((int) total_read);
    }

    public Message[] removeDecodedMessages() {
        if (messages.isEmpty())
            return null;

        Message[] msgs = (Message[]) messages.toArray(new Message[messages.size()]);

        messages.clear();

        return (msgs);
    }

    public int getProtocolBytesDecoded() {
        return (protocol_bytes_last_read);
    }

    public int getDataBytesDecoded() {
        return (data_bytes_last_read);
    }

    public int getPercentDoneOfCurrentMessage() {
        return (0);
    }

    public void pauseDecoding() {
    }

    public void resumeDecoding() {
    }

    public ByteBuffer destroy() {
        destroyed = true;

        return (null);
    }
}
